Circuits used in electrical devices are typically designed from functional circuit blocks (FCBs), where each of these blocks is designed to carry out predetermined processes within the electrical device. Power consumption plays an increasingly important role in modem devices that are being provided with increased functionality, but must maintain sufficient battery longevity in order for them to be sufficiently useful between battery recharge operations. For instance, cellular telephones have become widespread, but in order for their continued usefulness they must be able to operate for longer periods of time; an issue that becomes more difficult when an ever increasing number of features are integrated therein, such as, for example, color LCD video displays, or encryption processes.
In a majority of electrical circuits that employ FCBs, clock signals are typically provided to each FCB from a clock signal source in order for that FCB to be able to process incoming signals and to provide output signals at output ports thereof. Clock signals controllably oscillate between a first potential and a second potential, the first and second potential on opposing sides of a switching threshold voltage. Furthermore, the clock signal is preferably a square wave type signal, with minimal ringing. Furthermore, FCBs coupled to the clock circuit receive the clock signal and gating circuitry within these FCBs consumes electrical power in response to the clock signal activating the gating circuitry.
It is therefore an object of the invention to provide an electrical device that is made up of a plurality of FCBs with each FCB having its own controllable clock source, where the clock signal is switched to an FCB on demand in dependence upon operational requirements of each FCB from the plurality.